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Jan 5, 2011 -- People with early rheumatoid arthritis (RA) who smoke are less likely to respond to treatment with two of the most commonly used medications -- an older disease modifying antirheumatic drug called methotrexate and biologic drugs known as TNF blockers, according to a new study in January’s Arthritis & Rheumatism.

RA is an autoimmune disease that occurs when the body’s immune system misfires against its own joints and tissues, resulting in inflammation, swelling, pain, and ultimately the loss of mobility. Treating RA early with disease-modifying antirheumatic medications is considered the best way to stop this progressive disease in its tracks.

“Our findings indicate that cigarette smokers have a diminished chance of responding well to the currently first- and second-line agents of choice in early RA treatment today,” conclude researchers who were led by Saedis Saevarsdottir, MD, PhD, a rheumatologist at the Karolinska University Hospital in Stockholm, Sweden.

Exactly how smoking affects response to RA treatment is not fully understood, but one theory suggests smokers may metabolize some RA medications differently than nonsmokers, which could compromise its effectiveness.

Of 1,430 people with early RA who were part of a Swedish registry, 873 started therapy with methotrexate and 535 started taking anti-TNF drugs within about three years of their RA diagnosis.

If they smoked (27% of them were current smokers), participants were less likely to show a good response to treatment with methotrexate or anti-TNF drugs at three months, six months, one year, and five years out when compared with their counterparts who never smoked.

Past Smokers

Those study participants who had smoked in the past did not experience a muted response to treatment when compared to those individuals who never smoked, the study showed.

Treatment response was based on guidelines put out by the European League against Rheumatism (EULAR), the European equivalent of the American College of Rheumatology, and based on the number and degree of painful joints and other measures of disease activity.

It is still too early to tell whether quitting smoking will improve response to therapy, but it seems plausible based on the fact that past smokers responded as well to therapy as never smokers, the researchers write.

“The findings provide a strong impetus for clinicians to include measures against smoking as a fundamental part of their therapeutic armamentarium in RA care,” the researchers write.

“This is a very interesting study that provides further information on the impact of smoking on RA,” says David Pisetsky, MD, chief of rheumatology at Duke University Medical Center in Durham, N.C, in an email.

Exactly how smoking affects treatment response is not fully understood, he says. “Likely, it causes chronic inflammation which exacerbates the underlying problem in RA and limits response to therapy. Patients who smoke should definitely stop, but it may be particularly difficult given the stress of a chronic disease as well as potential effects of nicotine on pain perception.”

More Reasons to Quit Smoking

Previous research has shown that smoking can raise the risk for developing RA, says Theodore Fields, MD, clinical director of the Early Arthritis Initiative at the Hospital for Special Surgery in New York City. “If you are at risk for RA, such as having RA in your family, don’t smoke because it does seem to be associated with onset and some data also suggest that it worsens RA that is already there.”

“This new study suggests that if you are a smoker, you are less likely to respond well to the most commonly used drugs. So the message is, if you are at risk of RA, don't smoke -- and if you already have RA, stop smoking,” he says. “We can’t say that stopping short-term will make you respond better, but the data is suggestive. The fact that people who were still smoking did worse suggests that it’s a good idea to stop.”

This new information may help people with RA quit smoking, he says. “Smoking is bad for your lungs and for your heart, but you are less likely to respond to RA treatment, and that may be one more stimuli for a patient to stop.”